1. Field of the Invention
The present invention relates to an eyepiece used with microscopes (esp., stereoscopic ones), etc. and, more particularly, to an eyepiece that is inexpensive and has an improved image surface flatness.
2. Description of the Related Art
Eyepieces similar to that disclosed herein and known in the art, for instance, are set forth in JP-A-63(1988)-318514 and 62(1987)-255914, the former made up of three lens groups, each consisting of three lens elements, at least one of which is formed of a plastic lens having an aspherical surface, and the latter mainly made up of two lens groups, each consisting of three lens elements, at least one surface of which is aspherical.
These conventional eyepieces have some drawbacks; the former, comprising three lens components, is less than satisfactory in terms of the correction of pupil and chromatic aberrations (esp., chromatic aberration of pupil) for lack of any cemented surface, and the latter is still insufficient in terms of the flatness of the image surface when the field angle is further widened.